IEEE 802.11ah网络能效优化的RAW适配机制

为支持大规模终端设备的机器与机器(machine to machine，M2M)应用，IEEE 802.11ah协议在MAC层引入了限制接入窗口(restricted access window，RAW)机制，以减少同时进行随机接入的终端设备数量、降低碰撞概率。基于上行链路通信的RAW能效优化问题，提出了RAW时隙适配机制。该机制应用概率理论评估RAW时隙中发送数据包时工作站(station，STA)可能处于不同状态的概率，根据RAW时隙中平均分配的终端设备数量自适应调整RAW的时隙持续时间，从而优化RAW上行链路的能效。仿真结果表明，提出的机制可以显著提高上行链路吞吐量和能效，能更好地满足大规模低功耗高能效的M2M应用需求。

Adaptively adjusting RAW slot for energy efficiency optimization in IEEE 802.11ah networks

In order to support the machine to machine (M2M) applications of large-scale terminal devices, IEEE 802.11ah protocol introduces the restricted access window mechanism in MAC layer to reduce the number of terminal devices with random access at the same time and in turn reduce the collision probability. Based on the problem of raw energy efficiency optimization in uplink communication, a raw slot adaptation mechanism is proposed. This mechanism uses probability theory to estimate the probability that the station (STA) may be in different states when sending packets in raw slot, and adaptively adjusts the slot duration of raw according to the average number of terminal devices allocated in raw slot, so as to optimize the performance of raw uplink. Simulation results show that the proposed mechanism can significantly improve the uplink throughput and energy efficiency, and can better meet the requirements of large-scale M2M applications with low power consumption and high energy efficiency.